docs: def Jung_Radermacher(m, x, rhol, rhog, mul, mug, D, roughness=0, L=1):
      r'''Calculates two-phase pressure drop with the Jung-Radermacher (1989)
      correlation, also shown in [2]_ and [3]_.
  
      .. math::
          \frac{\Delta P_{tp}}{\Delta P_{lo}} = \phi_{tp}^2
  
      .. math::
          \phi_{tp}^2 = 12.82X_{tt}^{-1.47}(1-x)^{1.8}
  
      Parameters
      ----------
      m : float
          Mass flow rate of fluid, [kg/s]
      x : float
          Quality of fluid, [-]
      rhol : float
          Liquid density, [kg/m^3]
      rhog : float
          Gas density, [kg/m^3]
      mul : float
          Viscosity of liquid, [Pa*s]
      mug : float
          Viscosity of gas, [Pa*s]
      D : float
          Diameter of pipe, [m]
      roughness : float, optional
          Roughness of pipe for use in calculating friction factor, [m]
      L : float, optional
          Length of pipe, [m]
  
      Returns
      -------
      dP : float
          Pressure drop of the two-phase flow, [Pa]
  
      Notes
      -----
      Applicable for 0 < x < 1. Developed for the annular flow regime in
      turbulent-turbulent flow.
  
      Examples
      --------
      >>> Jung_Radermacher(m=0.6, x=0.1, rhol=915., rhog=2.67, mul=180E-6,
      ... mug=14E-6, D=0.05, roughness=0, L=1)
      552.0686123725571
  
      References
      ----------
      .. [1] Jung, D. S., and R. Radermacher. "Prediction of Pressure Drop during
         Horizontal Annular Flow Boiling of Pure and Mixed Refrigerants."
         International Journal of Heat and Mass Transfer 32, no. 12 (December 1,
         1989): 2435-46. doi:10.1016/0017-9310(89)90203-2.
      .. [2] Kim, Sung-Min, and Issam Mudawar. "Universal Approach to Predicting
         Two-Phase Frictional Pressure Drop for Adiabatic and Condensing Mini/
         Micro-Channel Flows." International Journal of Heat and Mass Transfer
         55, no. 11–12 (May 2012): 3246-61.
         doi:10.1016/j.ijheatmasstransfer.2012.02.047.
      .. [3] Filip, Alina, Florin Băltăreţu, and Radu-Mircea Damian. "Comparison
         of Two-Phase Pressure Drop Models for Condensing Flows in Horizontal
         Tubes." Mathematical Modelling in Civil Engineering 10, no. 4 (2015):
         19-27. doi:10.2478/mmce-2014-0019.
      '''
      v_lo = m/rhol/(pi/4*D**2)
      Re_lo = Reynolds(V=v_lo, rho=rhol, mu=mul, D=D)
      fd_lo = friction_factor(Re=Re_lo, eD=roughness/D)
      dP_lo = fd_lo*L/D*(0.5*rhol*v_lo**2)
  
      Xtt = Lockhart_Martinelli_Xtt(x, rhol, rhog, mul, mug)
      phi_tp2 = 12.82*Xtt**-1.47*(1.-x)**1.8
      return phi_tp2*dP_lo